Volume determination of irregularly-shaped quasi-spherical nanoparticles

Abstract

Nanoparticles (NPs) are widely used in diverse application areas, such as medicine, engineering, and cosmetics. The size (or volume) of NPs is one of the most important parameters for their successful application. It is relatively straightforward to determine the volume of regular NPs such as spheres and cubes from a one-dimensional or two-dimensional measurement. However, due to the three-dimensional nature of NPs, it is challenging to determine the proper physical size of many types of regularly and irregularly-shaped quasi-spherical NPs at high-throughput using a single tool. Here, we present a relatively simple method that determines a better volume estimate of NPs by combining measurements from their top-down projection areas and peak heights using two tools. The proposed method is significantly faster and more economical than the electron tomography method. We demonstrate the improved accuracy of the combined method over scanning electron microscopy (SEM) or atomic force microscopy (AFM) alone by using modeling, simulations, and measurements. This study also exposes the existence of inherent measurement biases for both SEM and AFM, which usually produce larger measured diameters with SEM than with AFM. However, in some cases SEM measured diameters appear to have less error compared to AFM measured diameters, especially for widely used IS-NPs such as of gold, and silver. The method provides a much needed, proper high-throughput volumetric measurement method useful for many applications.

Collision, Adhesion, and Oxidation of Single Ag Nanoparticles on a Polysulfide-Modified Microelectrode

“…An important study by Attota et al explored the error of the 2D projection method by simulating 3D NP models of a known volume with different degrees of surface roughness and nonsphericity. 40 They found that rough, faceted, and oblong NP geometries can have their volume overestimated by up to 18% using the same 2D projection method applied in TEM data analysis. Note that a constant percent overestimation leads to larger numerical differences for increased NP size.…”

Development of a new hybrid approach combining AFM and SEM for the nanoparticle dimensional metrology

“…Other NP populations were analysed on the same sample and similar results were found. As observed in another study, a systematic discrepancy between AFM and SEM has been measured with systematically lower values obtained during the AFM height measurements [23].…”

Application of Carbon Nanoparticles in Oncology and Regenerative Medicine

“…Increasingly, nanotechnological achievements are used in the biological and medical fields. This application is possible due to the production of nanoparticles, where the size does not exceed 100 nm [ 1 , 2 , 3 ]. Considering their origin, nanoparticles can be divided into: Natural and designed, and considering their structure, into spherical, fibrous and layered [ 4 ].…”